Convection Oven with Removable Grill Plate

ABSTRACT

A cooking appliance having a housing which includes a cooking chamber suitable for convection cooking and grilling. The appliance includes a plurality of heat sources positioned within the housing to generate heat within the cooking chamber, a power source for powering the plurality of heat sources, at least one fan for moving air within the cooking chamber, a removable grill plate which secures within the cooking chamber, and an outlet for connecting the removable grill plate to the power source when positioned within the cooking chamber.

RELATED APPLICATION

The present application claims the filing priority of U.S. ProvisionalApplication No. 63/154,935, titled “Convection Oven With Removable GrillPlate” and filed on Mar. 1, 2021. The '935 application is herebyincorporated by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to cooking appliances, specificallycountertop cooking appliances. More specifically, the invention relatesto countertop convection ovens with a removable grilling plate.

BACKGROUND OF THE INVENTION

Convection ovens are well-known in the art. Convection cooking—i.e.,cooking with heated air—creates a dry atmosphere within a cookingchamber that caramelizes food sugars faster when roasting. Foods, likemeats and vegetables, that are cooked using convection get browner, butthe interiors stay moist. Further, convection cooking saves energybecause food cooks faster in a convection oven, and generally at a lowertemperature. Convection ovens are typically a bit more energy efficientthan a regular oven.

Grilling is quite different from convection cooking, as it occurs withapplication of direct heat (radiation or conduction) to the food beinggrilled and can, therefore, be done in an open appliance. Grilling isalso typically done at higher temperatures than oven baking, whetherregular or convection. In many instances, food can be grilled to searouter surfaces and then finished in an oven.

However, in countertop cooking, the process of grilling and thenconvection oven cooking has always required two different appliances.Where countertop space is limited, having a single appliance which isversatile enough to handle both grilling and convection cooking would beof significant value, saving time, money, and space. Accordingly, acountertop appliance which is capable of both grilling and convectionoven cooking is needed.

Further, two keys to grilling any food well are to (1) maintain aconsistent cooking temperature for an entire cooking cycle, and (2)evenly distribute heat to the food being grilled. The first goal has todo with avoiding big temperature drops during the grilling process—i.e.,as a result of adding food to the grill surface or turning a grillingfood item over. The second goal has to do with avoiding hot and coldspots on a grilling surface—i.e., due to concentrated heat sources thatare ineffective across an entire grill surface. Prior art cookingappliances have difficulty accomplishing both of these goals. That is,the cooking surfaces for many appliances fluctuate too much during acooking cycle, and food cooking surfaces—e.g., grills—for prior artcooking appliances are designed such that heat is often localized,causing uneven grilling.

Until the invention of the present application, these and other problemsin the prior art went either unnoticed or unsolved by those skilled inthe art. By combining multiple functions into a single countertopappliance, versatility and transportability are improved, and cost andspace requirements are reduced.

The present invention provides a countertop cooking appliance whichperforms multiple functions with without sacrificing quality, design,style or affordability.

SUMMARY OF THE INVENTION

There is disclosed herein an improved cooking appliance which avoids thedisadvantages of prior devices while affording additional structural andoperating advantages.

Generally speaking, the cooking appliance comprises a housing havingformed therein a cooking chamber, a plurality of heat sources positionedwithin the housing to generate heat within the cooking chamber, a powersource for powering the plurality of heat sources, at least one fan formoving air within the cooking chamber, a removable grill plate whichsecures within the cooking chamber, and an outlet for connecting theremovable grill plate to the power source when positioned within thecooking chamber.

A grill plate for detachable connection to a power source within thedisclosed cooking appliance is also set forth. Generally speaking, thegrill plate comprises a top surface comprising a plurality of raisedribs, a heating element within the grill plate positioned so as to heatthe top surface, and a connector which allows the grill plate to beattached and detached from the cooking appliance and electricallycouples the heating element to a power source for the cooking appliance,wherein each of the plurality of raised ribs has a height and a width,and the height is equal to the width.

In specific embodiments, the second and third heating sources areinactive in the cooking appliance when the grill plate is engaged withthe power source within the cooking chamber. Power can be dividedbetween the grill plate and the first heating source. A user can alterthe power distribution between 0-100% for each of the components.

In specific embodiments of the grill plate of the cooking appliance, theplurality of raised ribs on the top surface comprises a height (h) and awidth (w), and the height (h) is preferably approximately equal to thewidth (w).

Preferably the height (h) and width (w) of each of plurality of raisedribs is in the range of from 5 mm to 8 mm. More preferably, the heightof each of the plurality of raised ribs is in the range of from 5.5 mmto 8 mm and the width is in the range of 5.0 to 7.0 mm. Most preferably,the height of each rib is 6.5 mm, and the width of each rib is 6.0 mm.

In specific embodiments, the plurality of raised ribs are preferablyequidistantly spaced a distance from one another on the top surface, thedistance being within the range of 10.2 to 13.8 mm and most preferably12 mm.

These and other aspects of the invention may be understood more readilyfrom the following description and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of facilitating an understanding of the subject mattersought to be protected, there are illustrated in the accompanyingdrawings, embodiments thereof, from an inspection of which, whenconsidered in connection with the following description, the subjectmatter sought to be protected, its construction and operation, and manyof its advantages should be readily understood and appreciated.

FIG. 1 is a perspective view of a prior art countertop convection oven;

FIG. 2 is a front view of the prior art countertop convection oven shownin FIG. 1;

FIG. 3 is a close-up view of an embodiment of a user interface controlpanel for the disclosed countertop convection oven;

FIG. 4 is a front perspective view of another embodiment of a countertopconvection oven with an insertable grill plate as described herein;

FIG. 5 is a close-up view of an embodiment of the door sensor for thedisclosed countertop convection oven;

FIG. 6 is a schematic illustrating an embodiment of a countertopconvection oven with insertable grill plate as described herein;

FIG. 7A is a top view of an embodiment of an insertable grill plate;

FIG. 7B is a close-up view of a portion of the grill plate of FIG. 6A;and

FIG. 8 is a schematic of a cut-away section of an embodiment of a grillplate to illustrate relative dimensions;

FIG. 9 is front edge view of the grill plate shown in FIG. 6A;

FIG. 10 is a temperature/time graph corresponding to data acquiredduring grilling using a prior art cooking appliance;

FIG. 11 is a temperature/time graph corresponding to data acquiredduring grilling using a cooking appliance of the present disclosure;

FIG. 12 is a temperature profile of an embodiment of the presentdisclosure;

FIG. 13 is a temperature profile for a prior art cooking appliance;

FIG. 14 is an electronic schematic of an embodiment of the disclosedcooking appliance illustrating operation when the door switch mechanismis activated; and

FIG. 15 is an electronic schematic of an embodiment of the disclosedcooking appliance illustrating operation when a temperature drop isdetected.

DETAILED DESCRIPTION OF THE INVENTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail at least one preferred embodiment of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the broad aspect of the invention to any of the specificembodiments illustrated.

Referring to FIGS. 1 and 2, a standard prior art convection ovenappliance 100 is shown. This appliance 100 is designed to be placed on acountertop and plugged into a power outlet. A built-in heat source isused to heat air within an interior cooking chamber 102 while a fan 104circulates the heated air. A control panel 106 on the exterior of theappliance 100 allows a user to manually set cooking temperatures,cooking time, fan speed, and other cooking parameters. The control panel106 may even provide pre-set cooking selections, such as “sear,”“reheat,” “defrost,” and the like.

Embodiments of the present invention are illustrated in FIGS. 3-5, wherethe cooking appliance is generally designated by the numeral 10. Theparticular illustrated cooking appliance 10 is of a countertopconvection oven with a removable grill plate 50.

As can be seen in FIGS. 3-6, the cooking appliance 10 includes a housing12 with a defined cooking chamber 14. A front opening of the chamber 14is covered by a downward pivoting door 16, preferably with a glasswindow 18. A plurality of tray/rack supports 20 may be provided alongsidewalls 22 of the chamber 14 to allow the insertion and removal ofcooking trays, wire racks 24, and a removable grill plate 50 (see FIG.4). A control panel 26 is positioned on a front face of the appliance10, either above or below the door 16.

The preferred cooking appliance 10 includes three heating sources 30. Afirst heating source 30A is positioned at the top surface of the cookingchamber 14 within the housing 12, while a second heating source 30B ispositioned at the bottom surface of the cooking chamber 14 withinhousing 12. A third heating source 30C is positioned at a rear wall ofthe cooking chamber 14 within housing 12 and includes a fan 32 forcirculating the heated air within the cooking chamber 14. Additionalfans may be provided. The positioning of the three heating sources 30has been found to provide the most advantageous cooking. However, otherlocations for any one or all of the heating sources 30 may be possible.Additional heating sources may also be used, as necessary. Each of theheating sources 30A-C and the fan 32 are electrically connected to thepower source—via standard wiring and use of, for example, AC plug 34—tofacilitate powering of these components.

FIG. 3 illustrates a user interface control panel 26 provided on anoutward front-face surface of the cooking appliance 10. The controlpanel 26 provides control of each of the heating sources 30, includingthe grill plate 50 when inserted. In a preferred embodiment, the bottomheating source 30B and rear heating source 30C are each deactivated whenthe grill plate 50 is inserted into the cooking chamber 14 and connectedto the power source outlet 36. The control panel 26 allows a user toenter time, temperature, cooking power, etc. as just some of thepossible control inputs.

FIGS. 4-6 show a grill plate 50 positioned in a bottom slot of thecooking appliance 10. The grill plate 50 provides an alternative directheat source to the cooking appliance 10 for both grilling andcombination cooking techniques.

When grilling, power is directed solely to the grill plate 50. Ifpreheating before grilling, the grill plate 50 and top heating source30A can be used to quickly reach a target grilling temperature. However,once the preheat is complete, only the grilling plate 50 is used. Priorart systems typically use air fry heaters or convection oven heaterswhile grilling, which has been found to dry out meats and results inless flavorful food product.

Combination cooking, aka “combo cooking,” allows a user to cook foodusing direct bottom heat from the grill plate 50 combined with topconvection heat from the first heat source 30A. The user can adjustpower to the grill plate 50 and the top heating source 30A, preferablyin 5% increments, for 100% total power—e.g., 65% power to grill plate 50and 35% power to heating source 30A.

The “Combo” cooking feature is only available when the grill plate 50 isconnected to the outlet 36 (FIG. 4). In order to engage the grill plate50, the user must press the [on/off] button 60 and then the [Combo]button 62. A 70% power to the grill plate 50 and 30% power to the topheating source 30A is a preferable default setting. However, otherdefault settings are possible, and the power percentages can be manuallyadjusted during use by turning dial 64. When the dial 64 is turned tothe right [+], power increases to the top heating source 30A up to 100%,while left [−] increases power to the grill plate 50 up to 100%.

As shown in FIG. 5, one of the key features of the disclosed cookingappliance 10 and grill plate 50 combination includes a door switch 40.When the pivoting door 16 is in an open position—even partially open—theswitch 40 signals a controller (not shown) to increase power to thegrill plate 50 and/or the first or top heating source 30A. The increasein power results in an increase in temperature at the grill plate 50,which is intended to overcome the loss of heat due to the open doorand/or the placement of a much cooler food item, e.g., steak, chicken,pork. FIGS. 14 and 15 show schematically the components which are usedto trigger the power increase as a result of a door open (FIG. 14) ortemperature drop (FIG. 15) condition.

Preferably, a 100° F. increase for less than five minutes, mostpreferably approximately two minutes (±10 seconds), is sufficient toovercome the heat loss. This power/heat boost is a particularly usefulfeature for grilling, as it is necessary to open the appliance door 16to add and turn over food items, such as burgers, steaks, chicken, andthe like. Maintaining the grill temperature ensures a proper searingtemperature, which is critical to locking in natural food juices duringgrilling. While a 100° F. increase for two minutes is preferred,certainly increases of less or more heat for longer or shorter periodsmay be suitable for other applications. Data in support of this feature,as compared to a prior art system, is shown in TABLE 1 below.

Referring to FIGS. 7A, 7B, 8 and 9, the grill plate 50 can be morereadily understood. As previously stated, the grill plate 50 provides adirect heating source for food when place onto the connected grill plate50. In a preferred embodiment, a connector 52 on a back edge of thegrill plate 50 connects to a corresponding outlet connector 36 withinthe cooking chamber 14 and allows the grill plate 50 to receive powerfrom the power source.

In a preferred embodiment, the grill plate 50 includes a top surface 54having a plurality of raised ribs 56—i.e., metal or ceramic ribs, asopposed to pork or beef ribs. The ribs 56 have specific dimensions whichfacilitate maintaining a consistent temperature during grilling. First,the ribs 56 are equidistantly spaced a distance (x) on the grill plate50, approximately 10.2 mm to 13.8 mm, measured center to center. Mostpreferably, the distance is approximately 12 mm, center to center.Further, the thickness or width (w) of each rib 56 is approximately thesame as the height (h) of the rib 56. The width (w) and height (h) ofeach rib should fall within the range of 5 mm to 8 mm. The range for theheight (h) is preferably 5.5 mm to 8 mm, with a most preferred height(h) of 6.5 mm. Similarly, the width (w) has a preferred measure in therange of 5 mm to 7 mm, with 6 mm being the most preferred width (w). By“approximately” it is meant that to an observer, without measurement,the dimensions appear equal—i.e., w=h. This near 1:1 relationshipcombined with the rib spacing has been found to help minimize heat lossof the grilling surface 54, which often happens when food is addeddirectly to the grill plate 50. The loss of heat results in inferiorgrilling. Significant loss of heat at the grilling surface duringgrilling can have a significant impact on the quality and taste ofgrilled food.

The grilling surface also comprises a plurality of holes 58 that releaseoil and food drippings into a pan below the grill plate 50. Drainingaway such material helps maintain the grill plate temperature as well.The plurality of holes 58 also result in less surface area to heat,which helps regulate the temperature, unlike prior art devices.

TABLE 1 below shows side-by-side temperature data of a prior artgrilling surface (left side of table) and the grilling surface of anembodiment of the present invention (right side of table). The data forthe two systems is also provided in graph form, as shown in FIGS. 10 and11.

To acquire the data provided in TABLE 1, a 16 oz. 1.5-inch steak was tobe cooked on each grill—ambient outside temperature of 67° F. (±1.0°F.). The present invention completed preheat at row A (8:20), while theprior art grill completed preheat at row B (8:50). The steaks wereturned at internal temperatures of 75° F., as shown by row C (14:20) androw D (15:10), for the present invention and prior art systems,respectively. Grilling was completed at row E (17:40) and row F (19:10).Each of the critical points A-F are indicated on the graphs of FIGS. 10and 11 as well.

TABLE 1 Time PRIOR ART GRILL PRESENT GRILL (mm:ss) Left Center RightInside Left Center Inside 00:00 71.60 71.60 71.60 70.88 71.96 73.0471.06 01:00 130.10 120.20 112.64 169.70 178.34 191.30 134.06 02:00189.32 171.50 160.16 246.38 255.20 274.64 197.96 03:00 256.82 211.64206.24 299.48 334.40 358.16 264.74 04:00 310.82 261.86 298.40 347.00402.80 427.64 326.66 05:00 340.70 353.12 337.64 379.04 442.04 464.90372.20 06:00 370.22 377.60 359.60 400.28 471.56 493.34 409.46 07:00401.54 395.42 385.52 409.46 499.28 519.98 436.10 08:00 415.04 413.24403.88 417.74 522.50 543.74 457.70 08:10 413.42 413.42 404.78 413.60525.92 546.80 461.12 08:20 418.64 418.28 410.36 419.18 529.52 550.58462.92 (A) 08:30 426.02 424.76 417.38 430.52 431.78 447.80 364.46 08:40435.56 431.78 424.76 440.06 387.50 377.96 397.22 08:50 417.02 402.80382.46 382.46 369.50 364.64 416.66 (B) 09:00 111.38 131.36 109.22 375.80357.08 356.54 417.20 09:30 127.58 129.74 123.62 410.00 348.26 342.68414.86 10:00 134.42 141.26 126.50 431.60 345.02 350.60 414.32 10:30154.40 161.24 132.44 448.34 352.04 357.62 413.42 11:00 158.18 204.26159.80 442.22 348.62 361.94 414.50 11:30 175.46 226.22 182.30 436.82353.84 364.46 413.24 12:00 204.62 255.02 205.88 452.48 369.14 368.60412.52 12:30 223.16 296.60 210.92 457.88 368.60 371.48 409.46 13:00228.38 310.46 218.30 444.92 381.38 374.36 406.94 13:30 229.46 299.48229.64 450.14 388.22 375.26 404.60 14:00 235.04 292.10 228.92 457.52392.72 385.88 402.80 14:10 233.24 297.14 230.72 455.72 387.14 386.42401.90 14:20 237.02 297.14 223.02 451.76 386.06 340.70 344.84 (C) 14:30233.60 299.48 235.76 456.44 300.02 288.50 356.00 14:40 231.62 298.40239.00 446.90 293.54 300.74 386.78 14:50 234.68 298.58 238.64 445.10279.68 310.64 392.90 15:00 235.22 300.74 241.52 449.06 269.42 308.66393.44 15:10 233.24 299.12 239.72 371.12 255.74 315.14 393.80 (D) 15:30216.68 246.74 352.94 413.96 253.58 336.56 394.70 16:00 235.94 249.80365.90 415.22 251.60 347.36 394.88 16:30 237.02 252.86 389.48 440.42269.06 354.20 396.14 17:00 241.34 258.08 396.68 450.86 277.16 370.94397.40 17:30 244.40 257.90 387.68 444.02 284.72 380.30 398.30 17:40244.76 257.36 388.94 444.56 282.56 376.52 398.84 (E) 18:00 245.84 259.70389.30 448.70 276.26 364.46 399.38 18:30 244.76 260.24 390.20 454.82276.62 370.40 399.74 19:00 243.50 258.26 380.30 453.02 264.20 360.86399.38 19:10 243.14 253.04 375.98 446.00 263.48 356.36 401.54 (F)

The temperature data shows that the prior art grill reached atemperature (° F.) of 417/402/382 after 8:50 (mm:ss) as measured at theleft, center, and right areas of the grill surface, respectively. Thetemperature immediately dropped to 111/131/109 ° F. upon addition of thesteak. This represents a drop of approximately 305/271/273 ° F. orroughly an average temperature loss of 70% (73%/67%/71%). Further, thegrilling temperature did not return to a proper grilling temperature ofapproximately 230° F. for at least three and a half minutes (13:00 minmark).

Conversely, the present invention reached a temperature of 530/550 ° F.(left and center) at 8:20 and dropped to 431/447° F. after addition ofthe steak. The temperature loss of 98/103° F. represents an average ofunder 19% drop (i.e., 18.5%/18.7%). More importantly, the grill surfacereturned to a proper grilling temperature of 370/365° F. by the 8:50mark—i.e., in less than 30 seconds. Finally, grilling of the steak wascompleted by the present invention at least 90 seconds prior to theprior art system.

During grilling, the present cooking appliance 10 adjusts the powerlevel of the two heating elements together—i.e., grill plate 50 andheating source 30A—in order to maintain the grill plate 50 surfacetemperature. The result is a steady, even temperature profile as shownin FIG. 12. With reference to FIG. 14, as soon as the door 16 is opened,the door switch 40 activates. This triggers the controller IC 70 toprovide full power (1000W) to the grill plate 50 and fan 32 forapproximately two minutes. Likewise, if the temperature sensor for thegrill plate 50, preferable an NTC thermistor 72, reacts to a temperaturedrop (e.g., 5-10° F.), the controller IC 70 is triggered to provide fullpower (1000W) to the grill plate 50 and fan 32 for approximately twominutes. Of course, as previously noted, these numbers are exemplary.That is, the power increase used may vary and the trigger point may beless than 5° F. or more than 10° F. for specific cooking operations.

Conversely, prior art devices never use a top and bottom grill heatertogether. Instead, they work alternately to create a fluctuating grillsurface temperature, as shown in FIG. 13.

The matter set forth in the foregoing description and accompanyingdrawings is offered by way of illustration only and not as a limitation.While particular embodiments have been shown and described, it will beapparent to those skilled in the art that changes and modifications maybe made without departing from the broader aspects of applicants'contribution. The actual scope of the protection sought is intended tobe defined in the following claims when viewed in their properperspective based on the prior art.

What is claimed is:
 1. A cooking appliance comprising: a housing havingformed therein a cooking chamber; at least three heat sources positionedwithin the housing to generate heat within the cooking chamber; a powersource for powering the three heat sources; at least one fan for movingair within the cooking chamber; a removable grill plate which secureswithin the cooking chamber, the removable grill plate having a topsurface, the top surface having a plurality of raised ribs; and anoutlet for connecting the removable grill plate to the power source whenpositioned within the cooking chamber.
 2. The cooking appliance of claim1, wherein each of the plurality of raised ribs comprises a height and awidth, and the height is equal to the width.
 3. The cooking appliance ofclaim 1, wherein each of the plurality of raised ribs are equidistantlyspaced a distance from one another on the top surface, wherein thedistance is within the range of 10.2 to 13.8 mm.
 4. The cookingappliance of claim 3, wherein the distance is 12 mm.
 5. The cookingappliance of claim 2, wherein the height and width of each of pluralityof raised ribs is in the range of from 5 mm to 8 mm.
 6. The cookingappliance of claim 5, wherein the height of each of the plurality ofraised ribs is in the range of from 5.5 mm to 8 mm.
 7. The cookingappliance of claim 5, wherein the height of each of the plurality ofraised ribs is 6.5 mm.
 8. The cooking appliance of claim 2, wherein thewidth of each of the plurality of raised ribs is in the range of from5.0 mm to 7.0 mm.
 9. The cooking appliance of claim 8, wherein the widthof each of the plurality of raised ribs is 6.0 mm.
 10. The cookingappliance of claim 1, further comprising a door open switch.
 11. Thecooking appliance of claim 10, wherein the door open switch isconfigured to trigger an increase of power to the removable grill platewhen activated.
 12. The cooking appliance of claim 11, wherein theincrease of power has a limited duration.
 13. The cooking appliance ofclaim 12, wherein the limited duration is less than 5 minutes.
 14. Thecooking appliance of claim 13, wherein the limited duration isapproximately 2 minutes.
 15. A grill plate for detachable connection toa power source within a cooking appliance, the grill plate comprising: atop surface comprising a plurality of raised ribs; a heating elementwithin the grill plate positioned so as to heat the top surface; and aconnector which allows the grill plate to be attached and detached fromthe cooking appliance and electrically couples the heating element to apower source for the cooking appliance; wherein each of the plurality ofraised ribs has a height and a width, and the height is equal to thewidth.
 16. The grill plate of claim 10, wherein each of the plurality ofraised ribs are equidistantly spaced a distance from one another on thetop surface, wherein the distance is within the range of 10.2 to 13.8mm.
 17. The grill plate of claim 11, wherein the distance is 12 mm. 18.The grill plate of claim 10, wherein the height and width of each ofplurality of raised ribs is in the range of from 5 mm to 8 mm.
 19. Thegrill plate of claim 13, wherein the height of each of the plurality ofraised ribs is in the range of from 5.5 mm to 8 mm.
 20. The grill plateof claim 14, wherein the height of each of the plurality of raised ribsis 6.5 mm.
 21. The grill plate of claim 13, wherein the width of each ofthe plurality of raised ribs is in the range of from 5.0 mm to 7.0 mm.22. The grill plate of claim 16, wherein the width of each of theplurality of raised ribs is 6.0 mm.